Highlights
- •Smaller amygdala volume was found in patients with chronic low back pain (CLBP) than in control individuals.
- •The degree of volume difference was distinct between the left and right amygdala.
- •Both volumetric and surface analyses were used to localize these differences.
- •Hemispheric asymmetry was found (left greater than right) in both groups.
- •The above results were confirmed in 24 unmedicated patients with CLBP.
Abstract
Although preclinical and clinical data strongly support an association between the
amygdala and chronic pain by the presence of mood and cognitive disturbances in affected
individuals, little attention has been paid to morphometric measurement of the structure
in patients with chronic low back pain (CLBP). In the present study, magnetic resonance
volumetric and surface analysis, using FMRIB's integrated registration and segmentation
tool (FIRST), were performed to compare structural magnetic resonance imaging data
obtained from 33 patients with CLBP with those obtained from 33 demographically similar
healthy control individuals. Our results indicated that the normalized volumes of
the left and right amygdala were significantly smaller in the CLBP group than in the
control group. Detailed surface analyses further localized these differences. The
degree of volume reduction was different between the left and right amygdala, with
a greater involvement of the left side. Both groups exhibited similar significant
hemispheric asymmetry for the amygdala (left > right). Similar asymmetry was suggested
in the subgroup of 24 unmedicated patients. No significant correlations were found
between amygdala volumes and pain characteristics or depressive symptoms. Our study
provides in vivo imaging evidence of abnormal morphology of the amygdala in patients
with CLBP using a fully automated segmentation method.
Perspective
Our study found that patients with CLBP had statistically significantly smaller normalized
volumes of the bilateral amygdala, compared with healthy control individuals, with
a greater involvement of the left side. These results may help to characterize the
impaired affective-cognitive dimension in patients with chronic pain.
Graphical abstract

Graphical Abstract
Key words
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Article info
Publication history
Published online: September 29, 2015
Accepted:
August 5,
2015
Received in revised form:
June 7,
2015
Received:
January 13,
2015
Footnotes
Funded by National Natural Science Foundation of China grant 81501455.
The authors declare no competing conflict of interest.
Supplementary data accompanying this article are available online at www.jpain.org and www.sciencedirect.com.
Identification
Copyright
© 2015 American Pain Society. Published by Elsevier Inc. All rights reserved.